It has nothing to do with that. It's still a mass-release into the blood stream, just like you would do with the molecules in a drug. It gets distributed everyw

It has nothing to do with that. It's still a mass-release into the blood stream, just like you would do with the molecules in a drug. It gets distributed everywhere. It can't go to a specific target, there are not road signs in arteries and capillaries and there is no active propulsion. What makes it "targeted" is that only those nano-containers release the drug that happen to find specific conditions of the targeted tissue. Normal targeting with small molecules (of drugs) is done by "3D pattern matching" - the molecules of the drug fit into or onto target molecules. Doesn't work if you don't have specific target molecules. So in this case instead of targeting molecules they target something else, which you can't do with a normal drug since then the only targeting you have is the 3D shape of the drug molecule. Here is a visualization of a small molecule binding to a protein (also a small one here, they often are much larger and incredibly complex - but predictablly so, since their chemical structure detemines how they fold): https://www.youtube.com/watch?v=g2Zj23pipuY https://www.youtube.com/watch?v=g2Zj23pipuY It's not a drug molecule but the exact same principle. Here is an animation for a drug encapsulated in a nano shell: https://www.youtube.com/watch?v=emEua2eJp1U https://www.youtube.com/watch?v=emEua2eJp1U The problem of normal drugs is that their shape and structure cannot be solely determined by the function they have to perform at the target. As a drug designer you have to design them that a) They are delivered at all, which includes a lot of difficulties on its own, like oral drugs having to pass through the very active liver, or that it has to be hydrophilic to be transported in blood but hydrophobic to get through cell membranes into cells. b) Since you cannot control where they end up they get everywhere, and they meet a zillion molecules on their way. If they bind anywhere else but in their target site, which is likely given that drugs are small molecules and the number of potential binding sites is huge, it's what you get to hear about as "side effects" of the drug. So by putting the drug molecule into a container you now have the advantage that you separate transport and target selection from the drug action, and the drug designer can concentrate on the effect on the target without having to worry about how it gets there and undesirable interactions everywhere else. The nano containers are still distributed throughout the whole body though, they just won't open at non-target sites. Source: I took "Medicinal Chemistry: The Molecular Basis of Drug Discovery" when it was first offered on edX. I highly recommend it, the teacher, Prof. Erland Stevens, is great! Course: https://www.edx.org/course/medicinal-chemistry-molecular-basis-drug-davidsonx-d001x-1 https://www.edx.org/course/medicinal-chemistry-molecular-bas...